Important Chemical Tests

Question 1

What is the test for CO₂?

Answer 1

Pass through lime water, Ca(HO)₂.

Clear → milky

Question 2

What is the test for O₂?

Answer 2

Relight a glowing splint

Question 3

What is the test for H₂?

Answer 3

Light it and makes a squeaky pop.

Question 4

What is the test for ammonia (NH₃)?

Answer 4

Damp red litmus paper turns blue.

Question 5

What is the test for water?

Answer 5

Cobalt chloride paper blue → pink

Question 6

How do we test for sulphate ions?

Answer 6

We add barium chloride (BaCl₂)

A white precipitate of BaSO₄ is produced

Question 7

What does Silver Nitrate (AgNO₃) test for? (3 ions)

Answer 7

Chlorides- White precipitate produced
Bromides- Cream precipitate
Iodides- Yellow Precipitate

Question 8

What are the metal flame tests?

Answer 8

Na - yellow/ orange
Ca - Blue/green
K - Lilac 
Li - green
Cu - Green/ blue
Strontium - red
Barium- apple green 
Calcium- bright red

Question 9

How do we test for alkenes?

Answer 9

Yellow bromine water turns colourless

Question 10

How do we test for alkanes?

Answer 10

Yellow bromine water states yellow (No reaction)

Question 11

How do we test for Fe³⁺,Fe²⁺ and Cu²⁺?

Answer 11

We add dilute Sodium Hydroxide to create a coloured precipitate- Ionic equations are:
Fe²⁺ + 2OH⁻ → Fe(OH)₂ (Green)
Fe³⁺ + 3OH⁻ → Fe(OH)₃ (Brown)
Cu²⁺ +2OH⁻ → Fe(OH)₂ (Blue)

Question 12

How do you test for acids with a pH meter?

Answer 12

We add a metal carbonate and CO₂ will be produced (which we can pass through lime water and it will turn milky).